Method for Forming Part Having Structural Reinforcements

This invention was made with government support under DE-EE0009203 awarded by the U.S. Department of Energy. The government has certain rights in the invention.

The present disclosure relates to a method for forming a part having structural reinforcements, and more particularly, a method for forming a vehicle part having structural reinforcements.

The statements in this section merely provide background information related to the present disclosure and does not constitute prior art.

Injection molding is a process for the manufacture of parts, for example, automotive parts. Injection molding generally involves heating a material (e.g., thermoplastic) in the form of pellets to create a molten material. This molten material flows through the injection molding equipment and is injected through one or more flow fronts to fill a mold. Once inside the mold, the molten material then cools and solidifies to form a desired part shape (which is the shape of a cavity, or multiple cavities within the mold). Polymeric/plastic materials have displaced metals as they can be formed through injection molding to form complex structures with high levels of feature integration. However, intrinsic properties of polymeric materials are typically different than intrinsic properties of metals.

This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

In one form, a method of forming a part for a vehicle is provided. The method includes positioning a plurality of continuous fiber reinforcements within a mold cavity of a mold, filling the mold cavity including the plurality of continuous fiber reinforcements with molten resin, and injecting fluid into the mold cavity to hollow a center portion of the molten resin.

In variations of the method of the above paragraph, which can be implemented individually or in any combination: removing the fluid from the mold cavity after the hollow center portion is formed; wherein the fluid is water; the plurality of continuous fiber reinforcements are unidirectional continuous fiber reinforcements; the continuous fiber reinforcements may be selected individually or in combination from the following: glass fiber, carbon fiber, metallic, and/or natural fiber, the molten resin is inserted into the mold cavity from a first side of the mold and the fluid is injected into the mold cavity from a second side of the mold that is opposite the first side; the plurality of continuous fiber reinforcements are secured within the mold cavity by retaining features; the plurality of continuous fiber reinforcements are solid, unidirectional continuous fiber reinforcements; the plurality of continuous fiber reinforcements are spaced apart from each other within the mold cavity; the method includes injection molding; and positioning a projectile within the mold cavity, wherein the fluid injected into the mold cavity moves the projectile through the mold cavity to form the hollow center portion in the molten resin.

In another form, a method of forming a part for a vehicle is provided. The method includes positioning a plurality of continuous fiber reinforcements within a mold cavity of a mold, filling the mold cavity including the plurality of continuous fiber reinforcements with molten resin, injecting water into the mold cavity to hollow a center portion of the molten resin; and removing the water from the mold cavity after the hollow center portion is formed. The continuous fiber reinforcements positioned at or near a perimeter of the mold cavity.

In variations of the method of the above paragraph, which can be implemented individually or in any combination: the plurality of continuous fiber reinforcements are unidirectional continuous fiber reinforcements; the molten resin is inserted into the mold cavity from a first side of the mold and the water is injected into the mold cavity from a second side of the mold that is opposite the first side; the plurality of continuous fiber reinforcements are secured within the mold cavity by retaining features; the plurality of continuous fiber reinforcements are solid, unidirectional continuous fiber reinforcements; the plurality of continuous fiber reinforcements are spaced apart from each other within the mold cavity; the method includes injection molding; positioning a projectile within the mold cavity, wherein the water injected into the mold cavity moves the projectile through the mold cavity to form the hollow center portion in the molten resin; and the molten resin is a polymeric material.

In yet another form, a method of forming a part for a vehicle is provided. The method includes positioning a plurality of continuous fiber reinforcements within a mold cavity of a mold, securing the plurality of continuous fiber reinforcement within the mold cavity, positioning a projectile within the mold cavity, filling the mold cavity including the plurality of continuous fiber reinforcements and the projectile with molten resin, injecting water into the mold cavity to move the projectile through the mold cavity to form a hollow center portion in the molten resin, and removing the water from the mold cavity after the hollow center portion is formed. The continuous fiber reinforcements are positioned at or near a perimeter of the mold cavity and spaced apart from each other. The plurality of continuous fiber reinforcements are unidirectional continuous fiber reinforcements.

In yet another form, a method of forming a part of a vehicle is provided. The method includes positioning at least one fiber sock within a mold cavity of a mold, filling the mold cavity including the fiber sock with molten resin, injecting fluid into the mold cavity to hollow a center portion of the molten resin, and removing the fluid from the mold cavity after the hollow center portion is formed.

In a variation of the method of the above paragraph, the fiber sock is impregnated with resin within the mold.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

Referring to, a partis illustrated inand a mold or molding toolfor forming the partis illustrated in. In one form, the partmay be a part of a vehicle such as a cross member to support a frunk (i.e., storage space or trunk) in a front end of an electric vehicle (not shown). In another form, the partmay be a tailgate reinforcement in a pick-up truck, for example. It should be understood that the partmay be for other exterior components or interior components of a vehicle, any reinforcement component of a vehicle, or any component where reinforcement is desirable.

In the example illustrated, the partincludes a predetermined portionwhere enhanced stiffness and strength may be desired. The predetermined portionincludes a hollow cavityand a plurality of fiber reinforcements,(together referred to as fiber reinforcements) disposed (e.g., embedded) within a resin material (e.g., polymeric material). The hollow cavityis formed in the partusing the molding toolas will be described in more detail below. In the example illustrated, the predetermined portionof the part has a generally square cross-section and the fiber reinforcementsare located at respective corners of the predetermined portionaround the hollow cavity. For example, the fiber reinforcementis located in the upper, left corner of the portionof the part, the fiber reinforcementis located in the upper, right corner of the portionof the part, the fiber reinforcementis located in the lower, left corner of the portionof the part, and the fiber reinforcementis located in the lower, right corner of the portionof the part. In this way, the fiber reinforcementsare embedded within the partaround the hollow cavity, which enhances the strength and stiffness of the partat the predetermined portionof the part. In some forms, the predetermined portionof the partmay have a circular cross-section, rectangular cross-section, or any other suitable cross-section having a hollow cavity. In such forms, the plurality of fiber reinforcements are embedded within a perimeter of the part around the hollow cavity and extend in the same direction to enhance the strength and stiffness of the part.

In one form, the fiber reinforcementsmay be continuous fiber reinforcements where bundles called tows or tapes are oriented in the same direction (e.g., a direction extending along a length of the part) and woven or braided in specific patterns. The reinforcing fibers may be selected individually or in combination from the following fibers: glass fiber, carbon fiber, metallic fiber, and/or natural fiber (e.g., flax), for example. In another form, the fiber reinforcementsmay be unidirectional, continuous fiber reinforcements where the fibers are aligned parallel in one direction for enhanced strength and stiffness in such direction. In yet another form, the fiber reinforcementsmay be solid, unidirectional, continuous fiber reinforcements. The fiber reinforcementsare embedded within the partduring the forming process, which will be described in more detail below.

With reference to, the molding toolincludes a mold cavitythat has a shape that corresponds to a shape of a desired part. In one form, the mold toolcan be made of one or more parts that cooperate to define the mold cavity. In the example illustrated, the molding toolincludes first and second partsthat cooperate to form the mold cavity. A part injectoris associated with the molding tooland is configured to inject a first fluidinto the mold cavity. In some forms, the part injectormay include one or more nozzles that extend through at least a portion of a wall of the molding tooland into the mold cavity. The first fluidmay be a molten resin such as a single polymeric material. In some forms, the first fluidmay be made of different polymeric materials used to form a single molded part. A cavity injectoris also associated with the molding tooland is configured to inject a second fluidinto the mold cavity(i.e., into the first fluid within the mold cavity) to form a hollow cavity in the part. In some forms, the cavity injectormay include one or more nozzles that extend through at least a portion of a wall of the molding tooland into the mold cavity. The second fluidmay be an inert gas, water, or oil, for example. In another form, the second fluidmay be a polymer material. In the example illustrated, the part injectoris located at one side of the molding tooland the cavity injectoris located at another side of the molding toolthat is opposite the side where the part injectoris located. In some forms, the part injectorand the cavity injectormay be on the same side of the molding tool.

With reference to, a methodfor forming the partis described in detail below. At, the plurality of fiber reinforcementsare positioned within the mold cavitysuch that the fiber reinforcementsextend along a longitudinal direction of the molding tool. That is, the molding toolis open such that the mold cavityis accessible and the plurality of fiber reinforcementsare positioned within the mold cavityat or near a periphery of the molding tool(only fiber reinforcementsshown in the). The fiber reinforcementare positioned within the molding toolusing retaining featuresIn the example illustrated, the retaining featuresare brackets made of metal or plastic and are spaced apart along the length of the molding tool. As shown in, each retaining featureincludes a center portionand gripping portionsextending from the center portion. The center portionmay include one or more openingsextending therethrough such that the first and second fluids,may flow pass the retaining featurethrough the mold cavity. Each gripping portionincludes a pair of armsthat define a space that receives a portion of a respective fiber reinforcement. The armsmay be resiliently flexible so as to allow the armsto flex outward (i.e., away from each other) as the fiber reinforcementsare inserted within the space. When the fiber reinforcementsare secured to the retaining featuresthe fiber reinforcementsare secured relative to each other and relative to the molding tool.

In one form, the retaining featuresand the fiber reinforcementsare secured to each other such that the retaining featuresare supported by the fiber reinforcements(i.e., the retaining featuresare disconnected from the molding tool). In another form, the retaining featuresmay include a tab (not shown) that secures the retaining featuresto the molding tool, thereby further inhibiting the retaining featuresfrom moving during injection of the fluids,. In yet another form, the retaining featuresmay be made of a metal material and may be urged toward one or more magnets (not shown) associated with the molding tool(e.g., located outside of the mold cavityor within the molding tool). That is, the magnets may generate a magnetic field that urges the metal retaining featurestoward to the magnets, thus, positioning and retaining the retaining featureswithin the mold cavity.

With reference to, the retaining featuresmay be brackets located at respective ends of the mold cavityand secured to the molding toolvia one or more fasteners. The retaining featuresmay be made of plastic or metal. Ends of the fiber reinforcementsmay be coupled to the retaining featuresthereby further inhibiting the fiber reinforcementsfrom moving within the mold cavityduring injection of the fluids,. The ends of the fiber reinforcementsmay be coupled to the retaining featuresby crimping. In another form, the ends of the fiber reinforcementsmay be coupled to the retaining featuresby partially wrapping the ends around the retaining featuresin the mold cavity. In yet another form, the retaining featuresmay be made of a metal material and may be urged toward one or more magnets (not shown) associated with the molding tool(e.g., located outside of the mold cavityor within the molding tool). That is, the magnets may generate a magnetic field that urges the metal retaining featurestoward to the magnets, thus, further positioning and securing the retaining featureswithin the mold cavity.

In yet another form, the fiber reinforcements may have metal threads that form an outer jacket around and along the fiber reinforcement. In this way, magnets located external to the mold cavitymay generate a magnetic field that urges the fiber reinforcements toward the magnets, thus, further positioning and securing the fiber reinforcements within the mold cavity. In yet another form, metal clips may be located within the mold cavityand may be configured to clip onto portions of respective fiber reinforcements along a length of the fiber reinforcements. In this way, magnets located external to the mold cavitymay generate a magnetic field that urges the clips toward the magnets, thus, further positioning and securing the clips and fiber reinforcements within the mold cavity. It should also be understood that the plurality of fiber reinforcementsare preformed prior to being positioned or inserted into the mold cavityof the molding tool.

With reference back to, at, the mold cavityincluding the fiber reinforcementsis at least partially filled with the first fluid(). That is, the molding toolis closed after the fiber reinforcementsare secured within the mold cavityand the first fluidis injected into the mold cavityusing the part injector. In one form, the first fluidcompletely fills the mold cavitysuch that the first fluidcompletely surrounds the fiber reinforcementsand retaining featureswithout adjusting the molding tool. In another form, the first fluidat least partially fills the mold cavitysuch that the first fluidcompletely surrounds the fiber reinforcementsand retaining featureswithout adjusting the molding tool. In the example illustrated, the part injectorinjects the first fluidinto the mold cavityfrom one end of the mold cavity.

At, the second fluid(e.g., inert gas, water, oil, or a polymer) is injected into the mold cavityusing the cavity injectorto hollow a central portion of the molten resin (). That is, the second fluidis injected into the mold cavitysuch that it flows through the first fluidat a predetermined portion to hollow a central portion of the first fluid. In this way, the first fluidmay be forced toward the periphery of the molding tool, which facilitates the formation of the hollow cavityand the periphery or outer profile of the predetermined portionof the partonce the partcools and solidifies. In one form, the second fluidis injected into the mold cavityafter the mold cavityis at least partially filled with the first fluid.

At, the second fluidis removed from the solid part. In one form, the second fluidis removed from the solid partby opening the cavity injector(e.g., a valve associated with the cavity injector) and draining the second fluidfrom the solid part(). The molding toolis opened and the partincluding the fiber reinforcementsembedded therein and surrounding the hollow cavitymay be removed from the molding tool().

In yet another form, as shown in, the molding toolincluding pairs of retractable pinsmay be used to retain fiber reinforcementstherein instead of the retaining featuresand/or retaining featuresdescribed above. That is, each fiber reinforcementmay be retained in place by a pair of retractable pinsassociated within the molding tool(i.e., each fiber reinforcementis located between the pins) and extending into the mold cavity. The pinsmay retract into the molding toolonce the cavityis filled and additional fluid is injected into the mold cavityto fill in the void or space created by the retraction of the pins. It should be understood that the fiber reinforcementsare secured in place when the pinsretract into the molding tool. In another form not shown, each fiber reinforcement is retained in place by at least one retractable pin (not shown) that extends across the mold cavity to press a respective fiber reinforcement against an internal wall defining the mold cavity as the first fluid is being injected into the mold cavity. Each pin may retract into the molding tool as the fluid fills the cavityand additional fluid is injected into the mold cavity to fill in the void or space created by the retraction of the pins. It should be understood that the fiber reinforcements are secured in place when the pins retract into the molding tool.

The present disclosure provides a method for manufacturing a partthat includes the fiber reinforcementsembedded within a polymeric wall and surrounding the hollow cavity. In this way, the parthas enhanced stiffness and strength. The partalso has a reduced weight by the elimination of components such as steel reinforcements, for example.

With reference to, another methodfor forming partis described in detail below. The methodmay be similar or identical to the methoddescribed above, apart from any exceptions noted below. At, the plurality of fiber reinforcementsand a projectileare positioned within the mold cavity(). The fiber reinforcementsare positioned within the mold cavitysuch that the fiber reinforcementsextend along a longitudinal direction of the molding tool(only fiber reinforcementsare shown in the). The fiber reinforcementare secured to the molding toolwithin the mold cavityusing retaining features. In the example illustrated, the projectileis disposed within the mold cavityat an end and may be of a solid or hollow construction. In the example illustrated, the projectilehas a bullet shape. In another example, the projectilehas any suitable shape that is allowed to move through the first fluidwithin the mold cavity. It should be understood that the projectilehas a shape that is pre-formed prior to being disposed within the mold cavity.

At, the mold cavityincluding the fiber reinforcementsand the projectileis at least partially filled with the first fluid(). That is, the molding toolis closed after the fiber reinforcementsand the projectileare disposed within the mold cavityand the first fluidis injected into the mold cavityusing the part injector. In one form, the first fluidcompletely fills the mold cavitysuch that the first fluidcompletely surrounds the fiber reinforcementsand at least partially surrounds the projectile. In another form, the first fluidat least partially fills the mold cavitysuch that the first fluidcompletely surrounds the fiber reinforcementsand at least partially surrounds the projectile.

At, the second fluid(e.g., inert gas, water, oil, or a polymer) is injected into the mold cavityusing the cavity injectorto hollow a central portion of the first fluid(). That is, the second fluidis injected into the mold cavitysuch that it pushes or forces the projectilethrough a predetermined portion of the first fluidto hollow a central portion of the predetermined portion of the first fluid. In this way, the first fluidmay be forced toward the periphery of the molding tool, which forms the hollow cavityand the periphery or outer profile of the predetermined portionof the partonce the partcools and solidifies. In the example illustrated, the second fluidis injected into the mold cavitysuch that it pushes or forces the projectilefrom the one end of the mold cavitytoward another opposing end of the mold cavity. It should be understood that the projectileis spaced apart from the fiber reinforcementsas the projectilemoves through the mold cavity. It should also be understood that the thickness of the walls of the polymeric partis thinner than the thickness of the walls of the polymeric partformed without the projectile. Stated differently, the projectilemoving through the first fluidforces or pushes more of the first fluidtowards the periphery of the molding toolcompared to without the projectile. In this way, the thickness of the wall of the polymeric partis less than the thickness of the wall of the polymeric part.

At, the second fluidis removed from the solid part. In one form, the second fluidis removed from the solid partby opening the cavity injectorand draining the fluid from the solid part. The molding toolis opened and the partincluding the fiber reinforcementsand projectileembedded therein may be removed from the molding tool(). The partalso includes a hollow cavity.

With reference to, another methodfor forming partis described in detail below. The methodmay be similar or identical to the methods,described above, apart from any exceptions noted below. At, the fiber reinforcementis positioned within the mold cavitysuch that the fiber reinforcementextends along a longitudinal direction of the molding tool. The fiber reinforcementmay be secured to the molding toolwithin the mold cavity. In some forms, the fiber reinforcementmay be a woven fiber sock/tube. In other forms, the fiber reinforcementis a non-preformed, woven fiber sock/tube. Still, in other forms, the fiber reinforcementis a mesh, non-preformed, woven fiber sock/tube.

At, the mold cavityincluding the fiber reinforcementis at least partially filled with the first fluid(). That is, the molding toolis closed after the fiber reinforcementis disposed within the mold cavityand the first fluidis injected into the mold cavityusing the part injector.

At, the second fluid(e.g., inert gas, water, oil, or a polymer) is injected into the mold cavityusing the cavity injectorto hollow a central portion of the first fluid(). That is, the second fluidis injected into the mold cavitysuch that it flows through a predetermined portion of the first fluidto hollow a central portion of the first fluid. In this way, the first fluidmay be forced toward the periphery of the molding tool, which forms the hollow cavityand the periphery or outer profile of the predetermined portionof the partonce the partcools and solidifies. The fiber reinforcementis embedded within the wall of the partas the partcools and solidifies. In some forms, the fiber reinforcementmay expand toward a periphery of the mold cavityas the second fluidflows through the predetermined portion of the first fluid.

At, the second fluidis removed from the solid part(). In one form, the second fluidis removed from the solid partby opening the cavity injectorand draining the second fluidfrom the solid part. The molding toolis opened and the partincluding the fiber reinforcementembedded therein may be removed from the molding tool().

A projectile (not shown) may be positioned within the molding toolin an optional step to form the hollow cavity. That is, the second fluid(e.g., inert gas, water, oil, or a polymer) is injected into the mold cavityusing the cavity injectorsuch that it pushes or forces the projectile through a predetermined portion of the first fluidto hollow a central portion of the first fluid. In this way, the first fluidmay be forced toward the periphery of the molding tool, which forms the hollow cavityand the periphery or outer profile of the predetermined portion of the partonce the partcools and solidifies.

The present disclosure provides a method for manufacturing a partthat includes the fiber reinforcementimpregnated with resin material and embedded within a polymeric wall. In this way, the parthas enhanced stiffness and strength. The method of the present disclosure disposes a raw fiber sock into the molding toolinstead of a pre-impregnated fiber sock. In this way, the impregnation of the fiber sock of the present disclosure happens inside of the molding toolwhile the first fluidis being injected into the molding cavity.

Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word “about” or “approximately” in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.

As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.